A resident is inoculated at a vaccination site at Yongdinglu Sub-district of Haidian district in Beijing, China, March 14, 2021. Photo: Xinhua

Chinese leading vaccine producer China National Biotec Group (CNBG), a Sinopharm subsidiary, has submitted suggestions on booster shots of inactivated COVID-19 vaccines to the relevant Chinese authorities, media reported Sunday. 

Chen Kun, a CNBG official, released the information to media on Sunday at the China International Fair for Trade in Services (CIFTIS). He said that it is suggested that certain groups such as elderly people and some window service industry employees should receive booster shots six to 12 months following the second shot of inactivated vaccines.

Chen noted that experiments on animals showed that a booster six months after the second shot could increase the level of antibodies in recipients by 5-10 times, enhancing immunity effectiveness. 

Chen also stressed that experimental data had shown that CNBG's two-shot inactivated vaccines are still effective against major circulating mutations of the novel coronavirus.    

The report came as the Chinese national health authority announced on Sunday that more than 2.1 billion shots of COVID-19 vaccines had been administered in the country as of Saturday. 

In a previous interview with the Global Times, Zhang Yuntao, vice president and chief scientist of CNBG, suggested that vaccinated people in China can choose to receive booster shots when available after herd immunity is achieved in the country. 

China's top epidemiologist Zhong Nanshan has estimated that the country could build herd immunity by vaccinating at least 80 percent of its population by the end of the year.  

CNBG displayed seven products at the 2021 CIFTIS, including four COVID-19 vaccines, two COVID-19 drugs and a nucleic acid test kit at the fair. 

One of the drugs is the first in the world made from plasma donated by vaccine recipients that contains antibodies against the novel coronavirus.